The overall objective of the proposed project is to study coding of tactile stimuli in neural circuits from the face in albino rats. Four specific objectives are identified: (1) To describe the stimulus-response (S-R) coding transforms in trigeminal neurons of the medulla using a broad battery of parametrically varied mechanical stimuli, a wide variety of spike discharge analyses and measures, and single-unit microelectrode recording methods; (2) To determine whether the several different subnuclei of the trigeminal nuclear complex differ in their S-R coding capabilities, using modern microelectrode micromapping procedures; (3) To determine the changes in S-R profiles that occur between the 1st-order and 2nd-order levels of trigeminal tactile circuits; (4) To specify the cerebral and cerebellar destinations of axons from different subnuclei of the trigeminal nuclear complex using electrical stimulation ("backfire") techniques. Computer control and data analysis techniques will be used to reach these objectives. Together, these studies will help fill conspicuous gaps in knowledge regarding fine-grain localization of tactile neural circuits responsible for differential coding of important spatial and temporal features of delicate, natural stimuli.